2. Two 20.-newton forces act concurrently on an object. What angle between these forces will produce a resultant force with the greatest magnitude?

(1) 0°(2) 45°(3) 90.°(4) 180.°

3. A car traveling west in a straight line on a highway decreases its speed from 30.0 meters per second to 23.0 meters per second in 2.00 seconds. The car’s average acceleration during this time interval is

(1) 3.5 m/s2 east(2) 3.5 m/s2 west(3) 13 m/s2 east(4) 13 m/s2 west

4 In a race, a runner traveled 12 meters in 4.0 seconds as she accelerated uniformly from rest. The magnitude of the acceleration of the runner was

(1) 0.25 m/s2(2) 1.5 m/s2(3) 3.0 m/s2(4) 48 m/s2

5. A projectile is launched at an angle above the ground. The horizontal component of the projectile’s velocity, vx, is initially 40. meters per second. The vertical component of the projectile’s velocity, vy, is initially 30. meters per second. What are the components of the projectile’s velocity after 2.0 seconds of flight? [Neglect friction.]

6. A ball is thrown with an initial speed of 10. meters per second. At what angle above the horizontal should the ball be thrown to reach the greatest height?

(1) 0°(2) 30.°(3) 45°(4) 90.°

7. Which object has the greatest inertia?

(1) a 0.010-kg bullet traveling at 90. m/s(2) a 30.-kg child traveling at 10. m/s on her bike(3) a 490-kg elephant walking with a speed of 1.0 m/s(4) a 1500-kg car at rest in a parking lot

8. An 8.0-newton wooden block slides across a horizontal wooden floor at constant velocity. What is the magnitude of the force of kinetic friction between the block and the floor?

(1) 2.4 N(2) 3.4 N(3) 8.0 N(4) 27 N

9. Which situation represents a person in equilibrium?

(1) a child gaining speed while sliding down a slide(2) a woman accelerating upward in an elevator(3) a man standing still on a bathroom scale(4) a teenager driving around a corner in his car

10. A rock is thrown straight up into the air. At the highest point of the rock’s path, the magnitude of the net force acting on the rock is

(1) less than the magnitude of the rock’s weight, but greater than zero(2) greater than the magnitude of the rock’s weight(3) the same as the magnitude of the rock’s weight(4) zero

11. The diagram below shows a compressed spring between two carts initially at rest on a horizontal, frictionless surface. Cart A has a mass of 2 kilograms and cart B has a mass of 1 kilogram. A string holds the carts together.

The string is cut and the carts move apart. Compared to the magnitude of the force the spring exerts on cart A, the magnitude of the force the spring exerts on cart B is

(1) the same(2) half as great(3) twice as great(4) four times as great

12. An 8.0-newton block is accelerating down a frictionless ramp inclined at 15° to the horizontal, as shown in the diagram below.

What is the magnitude of the net force causing the block’s acceleration?

(1) 0 N(2) 2.1 N(3) 7.7 N(4) 8.0 N

13. At a certain location, a gravitational force with a magnitude of 350 newtons acts on a 70.-kilogram astronaut. What is the magnitude of the gravitational field strength at this location?

(1) 0.20 kg/N(2) 5.0 N/kg(3) 9.8 m/s2(4) 25 000 N•kg

14. A spring gains 2.34 joules of elastic potential energy as it is compressed 0.250 meter from its equilibrium position. What is the spring constant of this spring?

(1) 9.36 N/m(2) 18.7 N/m(3) 37.4 N/m(4) 74.9 N/m

15. When a teacher shines light on a photocell attached to a fan, the blades of the fan turn. The brighter the light shone on the photocell, the faster the blades turn. Which energy conversion is illustrated by this demonstration?

16. Which statement describes a characteristic common to all electromagnetic waves and mechanical waves?

(1) Both types of waves travel at the same speed.(2) Both types of waves require a material medium for propagation.(3) Both types of waves propagate in a vacuum.(4) Both types of waves transfer energy.

17. An electromagnetic wave is produced by charged particles vibrating at a rate of 3.9 × 108 vibrations per second. The electromagnetic wave is classified as

(1) a radio wave(2) an infrared wave(3) an x ray(4) visible light

18. The energy of a sound wave is most closely related to the wave’s

(1) frequency(2) amplitude(3) wavelength(4) speed

19. A sound wave traveling eastward through air causes the air molecules to

(1) vibrate east and west(2) vibrate north and south(3) move eastward, only(4) move northward, only

21. In the diagram below, an ideal pendulum released from position A swings freely to position B.

As the pendulum swings from A to B, its total mechanical energy

(1) decreases, then increases(2) increases, only(3) increases, then decreases(4) remains the same

22. The diagram below represents a periodic wave.

Which two points on the wave are out of phase?

(1) A and C(2) B and F(3) C and E(4) D and G

23. A dry plastic rod is rubbed with wool cloth and then held near a thin stream of water from a faucet. The path of the stream of water is changed, as represented in the diagram below.

Which force causes the path of the stream of water to change due to the plastic rod?

(1) nuclear(2) magnetic(3) electrostatic(4) gravitational

24. A distance of 1.0 x 10-2 meter separates successive crests of a periodic wave produced in a shallow tank of water. If a crest passes a point in the tank every 4.0 x 10-1 second, what is the speed of this wave?